/Engine/Plugins/Media/PixelStreaming/Source/PixelStreamingHMD/Public/PixelStreamingHMD.h
Adjusts the viewport rectangle for stereo, based on which eye pass is being rendered.
virtual void AdjustViewRect ( int32 ViewIndex, int32 & X, int32 & Y, uint32 & SizeX, uint32 & SizeY ) const